As low-power mobile communication systems have become more common, there has been increased market pressure to reduce power in both mobile stations and in base stations. Such a reduction in power not only allows for lower energy costs, but also allows for lower cost and more compact circuit implementations. As the power consumption of transmission equipment is reduced, there is a corresponding reduction in the need for cooling equipment and for electronic components that are performance rated for high temperature operation. Moreover, lower power equipment is often physically smaller than their higher power consuming counterparts.
In a radio frequency (RF) transmission system, one of the primary power consumers is the RF power amplifier. In some systems, a power efficient signaling scheme is used to increase the efficiency of the systems. For example, the constant envelope Gaussian Minimum Shift Keying (GMSK) used in GSM systems is very efficient because the power amplifier may be operated closer to compression, and/or because the GSM signaling scheme lends itself toward the use of highly efficient power amplifiers, such as Class E amplifiers.
As the need for high data bandwidths are increasing, however, more systems, such as LTE and WiMAX are utilizing signaling schemes that have high peak to average power ratios (PAPR). While these high PAPR signaling schemes are highly bandwidth efficient, they generally consume more power than some power efficient signaling schemes because the power amplifier that transmit signals with high PAPR are operated in a less efficient back-off condition.